This application requests five years of support for the Center for Demography and Ecology, University of Wisconsin-Madison. CDE is a world-class research center in population research with affiliates in 10 departments and 4 colleges. It has held an NICHD P30 Population Center Grant since 1972; this application requests continuation of that support under NICHD's Population Research Infrastructure Program (R24). Support is requested for four research support cores - Administration, Computing, Information Services and Methodology -- and for Developmental Infrastructure. The Population Center Grant would support an extraordinary collection of scholars with high rates of productivity. During the past five years, CDE has aggressively recruited top young scientists, strengthened ties and developed new forms of cooperation with departments, research centers and institutes having complementary missions. Our research portfolio has become more diverse, is more international in character, and covers a greater share of the life course than in the past. CDE researchers work on a broad spectrum of topics, but four clusters constitute our signature themes: Health and Mortality; Fertility, Families and Households; the Demography of Inequality; and Data and Methodology. In addition to outstanding research in each of these areas, CDE researchers produce enormous amounts of high-quality data for use by the population research community. The Center's impact is demonstrated further by the success of its junior scientists - graduate students, postdoctoral fellows and assistant professors - and by the scientific leadership provided by CDE researchers to the field of population and their respective disciplines. Investment in CDE would leverage substantial commitments from the University, a large portfolio of individual research grants and outstanding human and organizational resources to promote innovative research on population issues.